1. Field of the Invention
The invention relates to a hydraulic telescopic shock absorber having a cylinder in which a piston is movable by a piston rod extending through the cylinder cap, which piston divides the cylinder into two chambers. It relates further to such a shock absorber having a system of passages for the damping fluid by which the two cylinder chambers communicate with each other and with a damping fluid reservoir arranged outside of the cylinder, in which a plurality of said passages comprise resistance members for effecting a damping force during the stroke of the piston, and in which during a complete ingoing stroke as well as during a complete outgoing stroke of the piston at least one communication of the passages with the cylinder is closed by the piston.
2. Description of the Prior Art
Such shock absorbers can be used for damping the vertical movements which a vehicle body undergoes relative to the supporting wheel construction due to the springy suspension of said parts. When the vehicle is loaded more heavily the springs will be compressed so that the shock absorbers normally take a more contracted position. In order to have the damping of the motions of the vehicle body to be as good as possible in the whole range of loads of the vehicle, the damping force of the shock absorbers should be higher at a higher loading of the vehicle than at a lower loading. In other words, the damping force in both directions of movement should be higher in a more contracted position of the shock absorber than in a more expanded position.
Although shock absorbers in which the damping force is dependent on the position of the piston in the cylinder are already known, no such shock absorbers have been provided hitherto in which the damping forces in both directions of movement are higher in a more compressed position than in a more expanded position and in which the damping forces, which act during different portions of the stroke and in both directions can be adjusted readily from the outside.